What is Subacute bacterial endocaditis?
Subacute Bacterial Endocarditis (SBE) is a bacterial infection that produces growths on the endocardium
(the cells lining the inside of the heart). Subacute bacterial endocarditis usually (but not always) is caused
by a viridans streptococci (a type of bacteria); it often develops on abnormal valves after asymptomatic
bacteremias (bacteria traveling through the bloodstream) from infected gums, or from gastrointestinal,
urinary, or pelvic procedures.
Symptoms
Most patients present with a fever that lasts several days to 2 weeks. Nonspecific symptoms are common.
Cough, shortness of breath, joint pain, diarrhea, and abdominal or flank pain may be present. About 90
percent of patients will have heart murmurs, but murmurs may be absent in patients with right-sided heart
infections. A changing murmur is common only in acute endocarditis.
What are the duke criteria?
Who needs antibiotic prophylaxis for procedures? What procedures do you need
prophylaxis for?
Recommendations for patients with underlying heart condition
Dental procedures for which endocarditis prophylaxis is recommended1
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Dental extractions
Periodontal procedures including surgery, scaling, and root planing, probing, and
recall maintenance
Endodontic (root canal) instrumentation or surgery only beyond the apex
Subgingival placement of antibiotic fibers or strips
Initial placement of orthodontic bands but not brackets
Intraligamentary local anesthetic injections
Prophylactic cleaning of teeth or implants where bleeding is anticipated
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Prophylaxis is recommended for patients with high- and moderate-risk cardiac
conditions
Other procedures for which endocarditis prophylaxis is recommended
Respiratory tract
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Tonsillectomy and/or adenoidectomy
Surgical operations that involve respiratory mucosa
Bronchoscopy with a rigid bronchoscope
Gastrointestinal tract2
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Sclerotherapy for esophageal varices
Esophageal stricture dilation
Endoscopic retrograde cholangiography with biliary obstruction
Biliary tract surgery
Surgical operations that involve intestinal mucosa
Genitourinary tract
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Prostatic surgery
Cystoscopy
Urethral dilation
Prophylaxis is recommended for high-risk patients; it is optional for medium-risk
patients.
Prophylactic Regimens for Dental, Oral, Respiratory Tract, or Esophageal
Procedures. (Follow-up dose no longer recommended.) Total children’s dose should
not exceed adult dose.
I. Standard general prophylaxis for patients at risk:
Amoxicillin: Adults, 2.0 g (children, 50 mg/kg) given orally one hour before procedure.
II. Unable to take oral medications:
Ampicillin: Adults, 2.0 g (children 50 mg/kg) given IM or IV within 30 minutes before
procedure.
III. Amoxicillin/ampicillin/penicillin allergic patients:
Clindamycin: Adults, 600 mg (children 20 mg/kg) given orally one hour before
procedure. -ORCephalexin* or Cefadroxil*: Adults, 2.0 g (children 50 mg/kg) orally one hour before
procedure. -ORAzithromycin or Clarithromycin: Adults, 500 mg (children 15 mg/kg) orally one hour
before procedure.
IV. Amoxicillin/ampicillin/penicillin allergic patients unable to take oral medications:
Clindamycin: Adults, 600 mg (children 20 mg/kg) IV within 30 minutes before
procedure. -ORCefazolin*: Adults, 1.0 g (children 25 mg/kg) IM or IV within 30 minutes before
procedure.
*Cephalosporins should not be used in patients with immediate-type hypersensitivity
reaction to penicillins.
Cardiac Conditions Associated With Endocarditis:
High-risk category:
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Prosthetic cardiac valves, including bioprosthetic and
homograft valves
Previous bacterial endocarditis
Complex cyanotic congenital heart disease (e.g., single ventricle states,
transposition of the great arteries, tetralogy of Fallot)
Surgically constructed systemic pulmonary shunts or conduits
Moderate-risk category
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Most other congenital cardiac malformations (other than above)
Acquired valvar dysfunction (e.g., rheumatic heart disease)
Hypertrophic cardiomyopathy
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Mitral valve prolapse with valvar regurgitation and/or thickened leaflets
Conditions in which the risk of IE following invasive dental or surgical procedures is low — The
following conditions are associated with a low risk of IE. The value of antimicrobial prophylaxis prior to
dental and surgical procedures in these settings is generally considered to be negligible and endocarditis
prophylaxis is not recommended:
Physiologic, functional, or innocent heart murmurs
Atrial septal defect
Mitral valve prolapse without associated regurgitation or valvular leaflet thickening
Mild or hemodynamically insignificant tricuspid regurgitation
Coronary artery disease (including previous coronary artery bypass graft surgery)
Intracardiac lesions that have been repaired more than six months previously in which there is
minimal or no hemodynamic abnormality
Previous rheumatic fever or Kawasaki disease without valvular dysfunction
Cardiac pacemakers (intravascular and epicardial) and implanted defibrillators
Prophylactic Regimens for Genitourinary/Gastrointestinal Procedures:
I. High-risk patients:
Ampicillin plus gentamicin: Ampicillin (adults, 2.0 g; children 50 mg/kg) plus
gentamicin 1.5 mg/kg (for both adults and children, not to exceed 120 mg) IM or IV
within 30 minutes before starting procedure. 6 hours later, ampicillin (adults, 1.0 g;
children, 25 mg/kg) IM or IV, or amoxicillin (adults, 1.0 g; children, 25 mg/kg) orally.
II. High-risk patients allergic to ampicillin/amoxicillin:
Vancomycin plus gentamicin: Vancomycin (adults, 1.0 g; children, 20 mg/kg) IV over 1–
2 hours plus gentamicin 1.5 mg/kg (for both adults and children, not to exceed 120 mg)
IM or IV. Complete injection/infusion within 30 minutes before starting procedure.
III. Moderate-risk patients:
Amoxicillin: Adults, 2.0 g (children 50 mg/kg) orally one hour before procedure -ORAmpicillin: Adults, 2.0 g (children 50 mg/kg) IM or IV within 30 minutes before starting
procedure.
IV. Moderate-risk patients allergic to ampicillin/amoxicillin:
Vancomycin: Adults, 1.0 g (children 20 mg/kg) IV over 1–2 hours. Complete infusion
within 30 minutes of starting the procedure.
What precipitated the problem for this patient?
A number of factors predispose to the development of IE; these include IDU, prosthetic heart valves,
bacteremia induced by an invasive procedure or a vascular device, prior history of endocarditis, HIV
infection, and structural heart disease (see above). Less common causes include:Pregnancy, Arteriovenous
fistulas used for hemodialysis, Central venous and pulmonary artery catheters, Peritoneovenous shunts for
the control of intractable ascites, Ventriculoatrial shunts for the management of hydrocephalus, ulcerative
lesions of the colon due to carcinoma or inflammatory bowel disease, and certain organ transpantations.
What is Streptoccus viridans?
They are sensitive to penicillin (most strains) and erythromycin. Tetracyclines,
cephalosporins and co - trimoxazole are less effective. Combination therapy with a penicillin
and an aminoglycoside, or ceftriaxone and an aminoglycoside for two weeks is highly effective in
streptococcus viridans endocarditis.
Sites and Sources
mouth, normal flora
nasopharynx, normal flora
skin, normal flora
heart, pathogen
oropharynx, normal flora